Surface Properties Of Materials Research Articles

Ultrathin Al2O3 film modification on waterborne epoxy coatings by atomic layer deposition for augmenting the corrosion resistance

The polar channels formed by the curing of waterborne anticorrosive coatings compromise their water resistance, leading to coating degradation and metal corrosion. To enhance the anticorrosive performance of waterborne coatings, this study proposed a novel method of depositing ultrathin Al2O3 films on the surface of waterborne epoxy coatings by atomic layer deposition, a technique that can modify the surface properties of polymer materials by depositing functional films. The Al2O3-modified coatings exhibited improved sealing and barrier properties by closing the polar channels and surface defects and cracks. The surface structure and morphology of the modified coatings were characterized by x-ray photoelectron spectroscopy and scanning electron microscopy. The hydrophilicity and corrosion resistance of the modified coatings were evaluated by water contact angle measurement, Tafel polarization curve, and electrochemical impedance spectroscopy. The results indicated that the water contact angle of the Al2O3-modified coating increased by 48° compared to the unmodified coating, and the protection efficiency of the modified coating reached 99.81%. The Al2O3-modified coating demonstrated high anticorrosive efficiency and potential applications for metal anticorrosion in harsh marine environments.

Evaluating surface mechanical properties and wear resistance of Ti–6Al–4V alloy subjected to ultrasonic pulsed waterjet peening

The alloy Ti–6Al–4V is widely utilized in various industrial applications, yet its inherent susceptibility to mechanical wear and friction has led to performance limitations. Addressing this, surface modification techniques have been employed to improve material surface properties. Among these, ultrasonic pulsed waterjet (UPWJ) peening emerges as a viable solution due to its ability to improve surface characteristics without causing excessive plastic deformation, unwanted thermal effects, or surface contamination. This study is focused on the influence of UPWJ peening parameters, particularly traverse speeds ranging from 200 to 1000 mm/s, on wrought Ti–6Al–4V (grade 5). Comprehensive characterization encompassed surface roughness, scratch hardness, and reciprocating wear analysis. Post-test examinations, including FE-SEM, CLSM, and EDS were employed to provide detailed microstructural and elemental insights. The results revealed that traverse speeds between 800 and 1000 mm/s yielded a remarkable 55 % enhancement in scratch hardness. Additionally, wear behavior exhibited a correlation with UPWJ traverse speed; notably, a speed of 900 mm/s indicated a 12 % improvement in wear resistance under a 40 N load. This research highlights the interplay relationship between UPWJ peening parameters and Ti–6Al–4V's wear performance, contributing to its broader understanding and application potential.

Development of New Polyimide/Spirulina Hybrid Materials: Preparation and Characterization

This study presents the synthesis and characterization of polyimide (PI-2) films incorporated with spirulina powder for potential biomedical applications. The synthesis of PI-2 was achieved through a two-step polycondensation reaction using N-methyl-2-pyrrolidone (NMP) as the solvent. The incorporation of spirulina was systematically varied to investigate its effects on the structural and surface properties of the hybrid materials. Scanning electron microscopy revealed a tightly bound interface between spirulina and the PI-2 matrix, indicating effective dispersion and strong interfacial adhesion. Profilometry and Raman spectroscopy confirmed the homogeneous integration of spirulina within the polymer matrix, with resulting variations in surface roughness and chemistry. Contact angle measurements demonstrated altered wettability characteristics, with increased hydrophilicity observed with spirulina incorporation. Furthermore, blood component interaction studies indicated the variations in adhesion behavior observed for red blood cells, platelets, and plasma proteins. Water uptake studies revealed enhanced absorption capacity in PI-2 films loaded with spirulina, highlighting their potential suitability for applications requiring controlled hydration. Overall, this comprehensive characterization elucidates the potential of PI-2/spirulina hybrid materials for diverse biomedical applications, offering tunable properties that can be tailored to specific requirements.

Optimized 2D Bi[formula omitted]Se[formula omitted] thickness for broadband, high-performance, self-powered 2D/3D heterojunction photodetectors with multispectral imaging capability

The hybrid 2D/3D heterostructure, which synergistically combine the high surface area and superior surface properties of 2D materials with the volumetric advantages and mechanical stability of 3D materials, offer an efficient and unique platform for electronic, optoelectronic, and energy conversion applications. Although this structure offers numerous advantages, optimizing the performance of 2D/3D heterojunction devices still faces challenges such as interface control difficulty, doping uniformity, and scalability for mass production. To simplify and effectively optimize the performance of 2D/3D heterojunction devices, this study delves into the impact of the thickness of 2D Bi2Se3 films on the performance of Bi2Se3/GaN heterojunction photodetectors. In thinner Bi2Se3 films, a higher surface defect density increases carrier recombination efficiency, while in thicker films, an increase in internal defects impedes carrier transport. Our findings reveal an optimal film thickness that balances surface and internal defects, enhancing carrier dynamics and device performance. Remarkably, the Bi2Se3 (14.8 nm)/GaN heterojunction detector exhibits superior broadband response from ultraviolet to near-infrared, with a maximum responsivity of 0.07 A/W, a detectivity of 1.79 × 1012 Jones, and an on/off ratio of 1.02 × 104. Additionally, the device demonstrates prolonged stability in response and multispectral imaging capability. This research not only underscores the critical role of film thickness in modulating device performance but also provides novel theoretical and practical guidance for designing high-performance, self-powered, broadband heterojunction photodetectors, offering significant implications for scientific research and practical applications.

Influence of Laser Treatment of Ti6Al4V on the Behavior of Biological Cells.

This article explores the enhancement of material surface properties of Ti6Al4V, potentially applicable to dental implants, through ultra-short pulse laser systems. This study investigates potential connections between surface wettability and biocompatibility, addressing the challenge of improving variability in material properties with specific laser treatment. Several designed microstructures were manufactured using a picosecond laser system. After that, the wettability of these structures was measured using the sessile drop method. The basic behavior and growth activity of biological cells (MG-63 cell line) on treated surfaces were also analyzed. While the conducted tests did not conclusively establish correlations between wettability and biocompatibility, the results indicated that laser treatment of Ti6Al4V could effectively enlarge the active surface to better biological cell colonization and adhesion and provide a focused moving orientation. This outcome suggests the potential application of laser treatment in producing special dental implants to mitigate the issues during and following implantation.

Effective removal of nitrate and phosphate using graphene nanosheets synthesized from waste plastics

In this work, waste plastics have been used with bentonite clay to produce silica-containing graphene nanosheets (GNs) for adsorption of nitrate and phosphate from synthetic water. The GNs were obtained by the two steps process, namely (1) pyrolysis at 750 °C and (2) ball milling. Then, GNs were characterized by Raman spectroscopy, FTIR, XRD, FESEM, HRTEM and EDX spectroscopy, which provided the details of material's morphology, surface properties, and composition. From Raman spectroscopy, D and G bands were found at 1342 cm−1 and 1594 cm−1, respectively, which confirmed the presence of nanosheets on the graphene surface. Furthermore, the layers of nanosheets were confirmed by the HRTEM analysis and XRD peaks. In analytical study, the batch experiment was conducted to investigate the influence of operational parameters such as pH (03–12), contact time (05–120 min), adsorbent dosage (0.01–0.06 g), and initial concentrations of adsorbates (10–50 mg/L for nitrate and 03–15 mg/L for phosphate) on adsorption process. The removal percentage of nitrate and phosphate at optimum dosage = 0.05 g, pH = 6.5, contact time = 60 min, nitrate concentration = 30 mg/L, and phosphate concentration = 09 mg/L were found to be 85 and 91, respectively. The highest adsorption capacity of nitrate and phosphate was found to be 53 mg/g and 16.4 mg/g, respectively. The adsorption behaviour of both nitrate and phosphate showed chemisorption as the experimental data were well fitted by the pseudo-2nd-order kinetic and Langmuir isotherm model. Life cycle cost analysis (LCCA) of the synthesis process was conducted to evaluate the cost-benefit analysis for commercial feasibility. The estimated price for the synthesis of GNs using 1 kg of waste plastics and bentonite clay as precursor was $4.21, suggesting commercialization.

Satellite design optimization for differential lift and drag applications

AbstractUtilizing differential atmospheric forces in the very low earth orbits (VLEO) regime for the control of the relative motion within a satellite formation is a promising option as any thrusting device has significant impact on system design due to the limited weight and size restrictions of small satellites. One possible approach to increase the available accelerations caused by the atmosphere is to reduce the mass of the respective satellites as well as to increase the available surface area. However, satellites of these characteristics suffer from rapid orbital decay and consequently have a reduced service lifetime. Therefore, achieving higher control forces is in contradiction to achieving a minimum orbital decay of the satellites, which currently represents one of the biggest challenges in the VLEO regime. In this article, the geometry of a given reference satellite, a 3UCubeSat, is optimized under the consideration of different surface material properties for differential lift and drag control applications while simultaneously ensuring a sustained VLEO operation. It is worth noting that both the consideration of sustainability as well as the optimization with regard to differential lift are new in literature. It was shown that the advantageous geometries strongly depend on the type of gas–surface interaction and thus, two different final designs, one for each extreme type, are presented. In both cases, improvements in all relevant parameters could be achieved solely via geometry adaptions.

Effect of radiotherapy on the surface roughness and microhardness of contemporary bioactive restorative materials.

The aim of this in vitro study was to evaluate the effect of radiotherapy on the surface microhardness and roughness of different bioactive restorative materials. A total of 60-disc specimens (5mm × 2mm) were performed in four groups (n = 15 each) from Equia Forte HT, Cention N, Activa Bioactive Restorative, and Beautifil II. Following the polishing procedure (600, 1000, 1200 grit silicon carbide papers), all specimens were irradiated at 2Gy per fraction, five times a week for a total dose of 70Gy in 30 fractions over 7weeks. Before and after the irradiation, the specimens were analyzed regarding the surface roughness and microhardness. Surface morphology was also analyzed by scanning electron microscopy. Kruskal-Wallis test, Wilcoxon test, and paired sample t-test were used for statistical analysis. Significant differences were found after radiation with increased mean roughness of both Cention N (p = 0.001) and Beautifil II (p < 0.001) groups. In terms of microhardness, only the Beautifil II group showed significant differences with decreased values after radiation. There were statistically significant differences among the groups' roughness and microhardness data before and after radiotherapy (p < 0.05). The effect of radiotherapy might differ according to the type of the restorative material. Although results may differ for other tested materials, giomer tends to exhibit worse behaviour in terms of both surface roughness and microhardness. In patients undergoing head and neck radiotherapy, it should be taken into consideration that the treatment process may also have negative effects on the surface properties of anti-caries restorative materials.

Bounding Volume Hierarchy-Assisted Fast SAR Image Simulation Based on Spatial Segmentation

In order to improve the simulation efficiency under the premise of ensuring the fidelity of synthetic aperture radar (SAR) simulation images, we propose a BVH-assisted fast SAR image simulation method based on spatial segmentation. The beam scanning model is established based on RD imaging geometric relation, and the bounding volume hierarchy (BVH) algorithm is used to assist in obtaining the time-varying latticed radiation and shadow areas within the radar beam, combining them with the real-time position of the sensors to complete the simulation of the electromagnetic (EM) wave transmission. The ray tracing algorithm is used to calculate the multiple backscatter fields of EM waves, including various material properties of the target surface. The SAR spatial traversal is adopted to spatially segment the latticed radiation area, and the compute unified device architecture (CUDA) kernel function is designed using the echo matrix cell method to make each cell of the target echo matrix as a subfield of the backscattering field, and the position of the echo matrix cell is traversed to obtain the target backscattering field. The target simulated echo is processed by the range Doppler (RD) imaging algorithm to obtain the SAR-simulated image. The simulation results show that compared with a CPU single-thread simulation, the simulation speed of the proposed method is significantly improved, and the SAR simulation image has high structural similarity with the real image, which fully verifies the effectiveness of the proposed method.

Experimental study on the radiation-induced destruction of organic compounds on the surface of the Moon

Volatile organic molecules and a complex organic refractory material were detected on the Moon and on lunar samples. The Moon’s surface is exposed to a continuous flux of solar UV photons and fast ions, e.g. galactic cosmic rays (GCRs), solar wind (SW), and solar energetic particles (SEPs), that modify the physical and chemical properties of surface materials, thus challenging the survival of organic compounds. With this in mind, the aim of this work is to estimate the lifetime of organic compounds on the Moon’s surface under processing by energetic particles. We performed laboratory experiments to measure the destruction cross section of selected organic compounds, namely methane (CH4), formamide (NH2CHO), and an organic refractory residue, under simulated Moon conditions. Volatile species were deposited at low temperature (17 - 18 K) and irradiated with energetic ions (200 keV) in an ultra-high vacuum chamber. The organic refractory residue was produced after warming up of a CO:CH4 ice mixture irradiated with 200 keV H+ at 18 K. All the samples were analyzed in situ by infrared transmission spectroscopy. We found that destruction cross sections are strongly affected (up to one order of magnitude) by the dilution of a given organic in an inert matrix. Among the selected samples, organic refractory residues are the most resistant to radiation. We estimated the lifetime of organic compounds on the surface of the Moon by calculating the dose rate due to GCRs and SEPs at the Moon’s orbit and by using the experimental cross section values. Taking into account impact gardening, we also estimated the fraction of surviving organic material as a function of depth. Our results are compatible with the detection of CH4 in the LCROSS eject plume originating from layers deeper than about 0.7 m at the Moon’s South Pole and with the identification of complex organic material in lunar samples collected by Apollo 17 mission.

Green Synthesis, Hybridization of SiO&lt;sub&gt;2&lt;/sub&gt; by Alkaline -Acid Leaching Method and their Optical and Structural Properties Using Rice Husk and &lt;i&gt;Anogeissus leiocarpus&lt;/i&gt; Extract

Silicon oxide is widely used as a thin film to improve the surface properties of materials, because it is of anti-resistance, hardness, corrosion resistance, dielectric, optical transparency and high delivery property etc. Therefore. Recent growing interest and efforts of scientists in this area are due to vitality in achievement of a better quality of life and health care for human beings, designing novel methods of making them more effective through hybridization with silver nanoparticles. Hence the need for nanoparticles capable of transmitting light with an ‘enhanced’ optical property for optoelectronics. In this study, silica was extracted from rice husk ash (RHA) using alkaline/acid leaching method, the AgNps was synthesized from Anogeissus leiocarpus extract using water extraction process, while the hybridization of silica with AgNps was carried out using in-situ and co-mixing method. Characterization was achieved using UV-Visible to confirmed the presence of silica at 290 nm, 291 nm, and 295 nm at different time intervals of 0, 60, 90. Changes in intensities of the bands indicate perfect hybridization with an enhancement in optical property. The XRD pattern of the silica-silver nanoparticles showed crystalline peaks at 2θ = 22.0o, 26.5o,29.5o 41o, which have been keenly indexed as face centred cubic Ago nanocrystals arising from Anogeissus leiocarpus extract. The increase in absorbance value of silica from (0.5 to 1.45, 1.50 respectively) confirms the improvement in optical properties of silica due to presence of AgNPs. The SEM analysis revealed the cap shaped spherical morphology and uniform size distribution of the nanohybrids within the range of 18.20 nm. Capping obtained is an evidence of organic matter in the plant extract. The percentage elemental compositions of Ag, Si, C and O in the nanohybrids were revealed by EDX analysis where Ag and Si are dominant. Therefore, silica-silver nanocomposite can be used as improved raw material in optical, ceramics and other relevant industries.

Hollow Porous Cu2S Nano-Spheres as High-Rate Magnesium Battery Cathode

The magnesium ion batteries are gaining huge attention in the field of battery energy due to high energy density, low cost potential and high safety performance. So far, the research of magnesium ion batteries has been slow. The surface and structural properties of cathode electrode materials greatly limiting the discharge performance of magnesium ion battery. Herein, a facile synthesis of Cu2S nano-hollow spheres for high performance magnesium ion battery cathode electrode materials was reported. This nano-hollow spheres have a large specific surface area (12.84 m2 g−1) which can reduce the volume expansion caused by magnesium ions during embedding and detachment, and facilitate ion diffusion during the discharge-charging process. Consequently, the nano-hollow porous Cu2S deliver a 152 mAh g−1 after 850 cycles at 560 mA g−1 hold a long-term cycling stability as cathode materials for magnesium ion battery. This work not only demonstrates the great potential of NHP-Cu2S materials, for application in magnesium ion batteries, but also sheds a new light on the application of metal sulfides in magnesium ion batteries.

Tuning low frequency dielectric properties of flexible ternary polymer blend film reinforced with bio- ionic liquid for the application in green electronics

Biofriendly conducting polymeric blends and composites exhibiting high dielectric constant and dielectric loss are promising for applications as sensors, actuators, microwave absorbing materials, fuel cells and biomedical applications. A great deal of work is reported on using fillers such as conductive nanomaterials, bio ceramics, carbon nanotubes, graphene etc in blends of Polyvinylchloride, Polyvinylpyrrolidone, Polymethylmethacrylate, Polyvinyl alcohol with conducting polymer Polypyrrole, Polyaniline for enhancing their conductivities, tailoring dielectric and electrical, thermal and surface properties of such polymeric materials. However, appropriate dispersion of such fillers in polymeric matrices remains technically challenging. In this regard, bio-ionic liquids have emerged as a novel class of materials and their combination with specific polymer blends opens the possibility to develop smart novel materials with different morphologies. Present work aims to explore the low frequency dielectric properties exhibited by free standing, flexible, biofriendly/biodegradable ternary polymer blend film of Polyvinylchloride-Polyvinylpyrrolidone-Polypyrrole reinforced with choline acetate. The detailed analysis of low frequency dielectric properties authenticates that addition of choline acetate result in modifying the dielectric properties of ternary polymer blend film.. The harmlessness of these films was confirmed from disk diffusion test indicating their benign nature towards (Escherichia coli) (CFT073) and (Bacillus subtilis). Therefore, the developed films can potentially be used for various scale multifunctional dielectric and electrical applications working in close contact with living matter, green electronics and various health monitoring systems.

Post-Production Finishing Processes Utilized in 3D Printing Technologies

Additive manufacturing (AM) has revolutionized production across industries, yet challenges persist in achieving optimal part quality. This paper studies the enhancement of post-processing techniques to elevate the overall quality of AM-produced components. This study focuses on optimizing various post-processing methodologies to address prevalent issues such as surface roughness, dimensional accuracy, and material properties. Through an extensive review, this article identifies and evaluates a spectrum of post-processing methods, encompassing thermal, chemical, and mechanical treatments. Special attention is given to their effects on different types of additive manufacturing technologies, including selective laser sintering (SLS), fused deposition modeling (FDM), and stereolithography (SLA) and their dedicated raw materials. The findings highlight the significance of tailored post-processing approaches in mitigating inherent defects, optimizing surface finish, and enhancing mechanical properties. Additionally, this study proposes novel post-processing procedures to achieve superior quality while minimizing fabrication time and infrastructure and material costs. The integration of post-processing techniques such as cleaning, surface finishing, heat treatment, support structure removal, surface coating, electropolishing, ultrasonic finishing, and hot isostatic pressing (HIP), as steps directly within the additive manufacturing workflow can immensely contribute toward this direction. The outcomes displayed in this article not only make a valuable contribution to the progression of knowledge regarding post-processing methods but also offer practical implications for manufacturers and researchers who are interested in improving the quality standards of additive manufacturing processes.

Concentration and reaction duration effects on synthesizing ZIF67 derivatives with NH4BF4 and NH4HF2 as efficient active material of energy storage device

Zeolitic imidazolate framework-67 (ZIF67) with large surface area and tunable pore structure is intensively applied as a tailoring target for design active materials. An in-situ tailoring technique is proposed to design ZIF67 derivatives by using structure directing agents (SDA) to induce favorable morphology and composition. Ammonium fluoride is a common SDA for modifying surface properties of active materials. With the same ammonium and similar fluorine-based groups, NH4BF4 and NH4HF2 are priming to play as SDA for synthesizing ZIF67 derivatives. In this study, the synthetic process of ZIF67 derivatives is tailored by varying the precursor concentration and reaction time in systems with NH4BF4 and NH4HF2 as SDA. The precursor concentration plays significant roles in the composition of ZIF67 derivatives. The reaction duration has higher influences on the morphology. The highest specific capacitance (CF) of 1347.0 F/g at 20 mV/s is achieved for the ZIF67 derivative synthesized using low concentration and 18 h, owing to favorable cobalt and nickel hydroxide compositions and two-dimensional sheet-like structure. An energy storage device composed of the optimal ZIF67 derivative and carbon electrodes shows a maximum energy density of 11.96 Wh/kg at 650 W/kg. The excellent cycling stability with CF retention of 83.6% and Coulombic efficiency of 92.0% is obtained after 10000 cycles.

Reciprocal interactions among parietal and occipito-temporal representations support everyday object-directed actions

Everyday interactions with common manipulable objects require the integration of conceptual knowledge about objects and actions with real-time sensory information about the position, orientation and volumetric structure of the grasp target. The ability to successfully interact with everyday objects involves analysis of visual form and shape, surface texture, material properties, conceptual attributes such as identity, function and typical context, and visuomotor processing supporting hand transport, grasp form, and object manipulation. Functionally separable brain regions across the dorsal and ventral visual pathways support the processing of these different object properties and, in cohort, are necessary for functional object use. Object-directed grasps display end-state-comfort: they anticipate in form and force the shape and material properties of the grasp target, and how the object will be manipulated after it is grasped. End-state-comfort is the default for everyday interactions with manipulable objects and implies integration of information across the ventral and dorsal visual pathways. We propose a model of how visuomotor and action representations in parietal cortex interact with object representations in ventral and lateral occipito-temporal cortex. One pathway, from the supramarginal gyrus to the middle and inferior temporal gyrus, supports the integration of action-related information, including hand and limb position (supramarginal gyrus) with conceptual attributes and an appreciation of the action goal (middle temporal gyrus). A second pathway, from posterior IPS to the fusiform gyrus and collateral sulcus supports the integration of grasp parameters (IPS) with the surface texture and material properties (e.g., weight distribution) of the grasp target. Reciprocal interactions among these regions are part of a broader network of regions that support everyday functional object interactions.

Plasma-Activated Polydimethylsiloxane Microstructured Pattern with Collagen for Improved Myoblast Cell Guidance.

We focused on polydimethylsiloxane (PDMS) as a substrate for replication, micropatterning, and construction of biologically active surfaces. The novelty of this study is based on the combination of the argon plasma exposure of a micropatterned PDMS scaffold, where the plasma served as a strong tool for subsequent grafting of collagen coatings and their application as cell growth scaffolds, where the standard was significantly exceeded. As part of the scaffold design, templates with a patterned microstructure of different dimensions (50 × 50, 50 × 20, and 30 × 30 μm2) were created by photolithography followed by pattern replication on a PDMS polymer substrate. Subsequently, the prepared microstructured PDMS replicas were coated with a type I collagen layer. The sample preparation was followed by the characterization of material surface properties using various analytical techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). To evaluate the biocompatibility of the produced samples, we conducted studies on the interactions between selected polymer replicas and micro- and nanostructures and mammalian cells. Specifically, we utilized mouse myoblasts (C2C12), and our results demonstrate that we achieved excellent cell alignment in conjunction with the development of a cytocompatible surface. Consequently, the outcomes of this research contribute to an enhanced comprehension of surface properties and interactions between structured polymers and mammalian cells. The use of periodic microstructures has the potential to advance the creation of novel materials and scaffolds in tissue engineering. These materials exhibit exceptional biocompatibility and possess the capacity to promote cell adhesion and growth.

Physical properties of asteroid Dimorphos as derived from the DART impact

AbstractOn 26 September 2022, NASA’s Double Asteroid Redirection Test (DART) mission successfully impacted Dimorphos, the natural satellite of the binary near-Earth asteroid (65803) Didymos. Numerical simulations of the impact provide a means to find the surface material properties and structures of the target that are consistent with the observed momentum deflection efficiency, ejecta cone geometry and ejected mass. Our simulation that best matches the observations indicates that Dimorphos is weak, with a cohesive strength of less than a few pascals, like asteroids (162173) Ryugu and (101955) Bennu. We find that the bulk density of Dimorphos ρB is lower than ~2,400 kg m−3 and that it has a low volume fraction of boulders (≲40 vol%) on the surface and in the shallow subsurface, which are consistent with data measured by the DART experiment. These findings suggest that Dimorphos is a rubble pile that might have formed through rotational mass shedding and reaccumulation from Didymos. Our simulations indicate that the DART impact caused global deformation and resurfacing of Dimorphos. ESA’s upcoming Hera mission may find a reshaped asteroid rather than a well-defined crater.

TEM and X-ray diffraction studies of structure of TiNi SMA treated by low-energy high-current electron beam

Advanced scientific and technological achievements in the surface engineering of TiNi shape memory alloys are closely related with their mechanical performance. Electron-beam treatments could be applied in order to modify surface properties of smart materials and promote stress-induced martensitic transformations. The fundamental issue of electron-beam processing is residual elastic stresses arising from the ultrafast quenching (∼108 K/s) of thin (∼2–4 μm) surface layers. We report the experimental results on phase composition, structure and residual elastic stresses formed in the binary TiNi SMA irradiated by a low-energy (< 25 keV) high-current (∼ 25 kA) electron beam. Microstructure, fracture mechanisms and phase analysis of the as-cast and deformed tensile specimens have been studied by X-ray diffraction and electron microscopy. After electron-beam treatment, both martensitic B19′ and R phases are found in the near surface layer. The X-ray diffraction studies indicate that compressive stresses in the B2 phase of the irradiated TiNi alloy reach –460 MPa. In the fractured specimen (after tensile test) the residual stresses decrease to –160 MPa and release through the B2→B19′→B2 martensitic transformation. In-depth gradient distribution of the defect substructures responsible for the mechanical behavior of TiNi alloys was revealed.

Tailless Information-Energy Metasurface.

Programmable metasurface technology can achieve flexible manipulations of electromagnetic waves in real time by adjusting the surface structure and material properties and has shown extraordinary potential in many fields such as wireless communications and the Internet of Things. However, most of the programmable metasurfaces have a common feature: a tail (electrical wires and DC powers), which is difficult to supply in some particular application scenarios such as canyons and mountains. To eliminate the limitation of DC power supply, the programmable metasurface and wireless power transfer technology are combined to propose a tailless information-energy metasurface (IEMS). The tailless IEMS platform can dynamically control electromagnetic waves without relying on an external DC power supply; instead, the required DC power is provided internally by the IEMS platform itself. In the tailless IEMS experiments, the concept is demonstrated through the dynamic regulation of wireless channels and the wireless transmission of DC power. This work provides a self-powered method for programmable metasurfaces, expands the application scenarios, facilitates the miniaturization of systems, and makes it easy to integrate with other systems.